The present invention relates to a lubricant composition and fuel-lubricant mixture useful for clean-up of two-stroke engines. Two-cycle engine technology has been around since the end of the 19th century, when it was invented in England. At first this technology was simple and early applications were primarily for motorcycles. Evinrude developed the first outboard engine in the United States in 1909 with a 1.5 HP engine. Because of their light weight characteristics, these engines are frequently used in handheld power tools, such as chainsaws, brushcutters, concrete saws, string trimmers, and lawn edgers. With time these simple carbureted two-cycle engines have become more complex and they have now become incorporated into new and modern recreational products, such as snowmobiles, jet skis and all terrain vehicles.
Two-cycle engine technology evolved in conjunction with these various applications. Exhaust port modifiers were added to the carbureted two-stroke engine in order to increase power over the entire rpm range, without any significant engine modifications and without negatively impacting the excellent power to weight ratio inherent to this engine design. Later direct fuel injection technology was developed in order to reduce hydrocarbon HC emissions. Some applications combined these direct fuel injection systems with exhaust port modifiers, while other applications incorporated only one of these features. Today, many of the modern two-cycle outboard engines have direct injection systems for both fuel and air. This technology was developed by Orbital and in some of the more modern applications it is also used in conjunction with exhaust port modifiers.
Additive lubricant technology has more slowly evolved to meet the increasing demands of these new technological improvements and enhancements to the two-cycle engine. Frequently, lubricants have been developed in response to engine design changes and rarely in advance or in anticipation of some imminent modification. In fact, the effect of engine modifications on lubricant requirements can rarely be accurately predicted in advance. As a result, many new consumer engines are operated using oils of inappropriate or inferior quality. In other cases, the consumer simply does not recognize or understand the need for special lubricants for these different applications. In both cases the result is the same. The use of poor quality oils or inappropriate lubricants for a given application can lead to engine deposits on pistons, cylinder walls, cylinder heads and variable exhaust systems. Over time, a continuous build-up of these deposits will cause a decrease in overall engine performance and in the most severe cases can cause engine seizure or catastrophic failure.
Traditionally, engine performance has been restored by disassembling the engine and cleaning it by hand. Once the engine parts are cleaned, the engine is then rebuilt with these cleaned and/or replaced engine parts. Because modern two-cycle engines have become increasingly complex, this approach takes time, as well as an in-depth knowledge of how to disassemble and rebuild a two-cycle engine.
EP1138753A2 discloses a lubricant composition for air-cooled two-stroke cycle engine having a Mannich detergent and an ashless dispersant, wherein the ratio of the Mannich detergent to the ashless dispersant is 3:1 to 5:1. The detergency additive provides detergency when used in a lubricating oil composition for air-cooled two-stroke cycle engines.
WO03/89555 discloses a low nitrogen content composition suitable for use in a direct fuel injection two-stroke engine comprising an oil of lubricating viscosity and a combination of three nitrogen containing dispersants.
The present invention, therefore, solves the problem of two-cycle engine clean-up, by providing a new lubricant composition and fuel-lubricant mixture that can clean up deposits formed and prevent deposits from being formed in a two-cycle engine. This can then eliminate the cumbersome task of needing to disassemble an engine in order to clean deposits off and restore the engine to an appropriate operating condition.